The present invention relates to injector/ejector mechanisms for circuit board modules and more specifically to a handle assembly for increasing the mechanical advantage of such mechanisms.
In recent years, open system architectures have been developed to provide mechanical and electrical compatibility between products of many different vendors. The VMEbus (IEEE Standard 1014) is an example of one such open system architecture. The VMEbus uses the "Eurocard" printed circuit board standard (IEC 297-3) to define the dimensions of VMEbus circuit board plug-in modules. These modules are mounted in a card cage mainframe that provides electrical power and interconnectivity through a backplane. Up to twenty modules can be installed in a standard mainframe having module guide rails spaced 0.8 inches apart.
The VMEbus modules are approximately six inches deep and four or nine inches high. Each module includes an appropriate size circuit board having a front panel mounted thereto. Handles are mounted on the front panel to aid in inserting and removing the modules from the mainframe. The smaller of the two modules has a single 96 pin electrical connector on the end opposite the front panel while the larger one has two connectors. The modules are generally installed vertically in the mainframe and connect with coextensive electrical connectors mounted on the backplane of the mainframe.
Attempts have been made to facilitate the insertion and removable of VMEbus modules into and out of the mainframe. U.S. Pat. No. 4,603,375, assigned to Zero Corp., describes a handle that is mounted on the front panel of a VMEbus module. The handle pivots bringing an ejecting surface formed on the handle into contact with mainframe front rail. Applying pressure to the handle causes the disengagement of the 96 pin electrical connectors from the coextensive connectors on the backplane.
A similar type of handle is manufactured by Elma Electronic Inc. of Fremont, California that has both an ejecting surface and an injecting surface. Pivoting the handle and applying pressure in one direction causes the injecting surface to engage the front panel rail to force the 96 pin connectors into the coextensive backplane connectors. Pivoting the handle and applying pressure in the opposite direction causes the ejecting surface to contact the front rail to disengage the the 96 pin connectors from the backplane connectors.
Based on the VMEbus architecture, a consortium of instrument manufactures developed the VXIbus (VMEbus Extensions for Instrumentation) architecture. The VXIbus maintains the mechanical and electrical standards of the VMEbus while adding and defining a third 96 pin connector requiring the addition of two new module sizes. These modules are approximately thirteen inches deep and nine and fourteen inches high and are placed on 1.2 inch centers. The addition of a third 96 pin connector in VXIbus modules increases the pressure required to insert and remove the modules. Prior art injecting/ejecting mechanisms do not have the mechanical leverage necessary to easily engage or disengage the electrical connectors in the larger size modules of the VXIbus architecture. In addition, the narrow width of the modules in conjunction with close packed spacing between the modules along with the precise placement of the front panel handles dictated by both the VMEbus and the VXIbus architectures makes it difficult for a user to grasp and apply pressure to the handles. Frequently, the user is injured attempting to insert or remove a module from the mainframe.
What is needed is a injector/ejector mechanism for use in VMEbus and VXIbus environment that provides greater mechanical advantage than prior art mechanisms while at the same time providing the user with an easy means of grasping and applying pressure to the mechanism.